1. Field of the Invention
The present invention relates to a transfer film, a transparent laminate, a method for producing the transfer film, a method for producing the transparent laminate, a capacitive input device, and an image display device. Specifically, the present invention relates to a capacitive input device which can detect a contact position of a finger by detecting a change in capacitance, a transparent laminate usable in the capacitive input device, a transfer film used for producing the transparent laminate, a method for producing a transfer film, a method for producing a transparent laminate using the transfer film, and an image display apparatus including the capacitance input device as a constituent.
2. Description of the Related Art
In recent years, in electronic instruments such as cellular phones, car navigations, personal computers, ticket vending machines, and banking terminals, a tablet-type input device has been mounted on the surface of a liquid crystal device or the like. When an instruction image is displayed on an image display area of the liquid crystal device, a user touches the site displaying the instruction image with a finger, a stylus, or the like with reference to the instruction image, and in this manner, information corresponding to the instruction image can be input.
Such an input device (touch panel) includes a resistive film-type input device, a capacitive input device, and the like. However, having a double-sheet structure consisting of a film and glass in which a short circuit is caused by pushing down the film the resistive film-type input device has defects such as a narrow range of operation temperature and vulnerability to temporal change.
In contrast, the capacitive input device has an advantage that it can be prepared simply by forming a light-transmitting conductive film on a sheet of substrate. Such a capacitive input device includes, for example, a type of input device which has electrode patterns extending in directions crossing each other, and detects an input position by detecting the change in capacitance between the electrodes when a finger or the like comes into contact with the device (for examples, see JP2010-86684A, JP2010-152809A, and JP2010-257492A).
At the time of using the aforementioned capacitive input device, for example, when a light source is projected on the device and thus regular reflection occurs, a transparent electrode pattern becomes noticeable in a position slightly distant from the vicinity of the position where the regular reflection occurs, and it makes the device unattractive. That is, the capacitive input device has a problem of visibility. In contrast, in JP2010-86684A, an ITO pattern is formed on a substrate, and only on the upper side of the ITO pattern, a layer formed of a dielectric material with a low refractive index such as SiO2 and a layer formed of a dielectric material with a high refractive index such as Nb2O5 are alternately laminated. JP2010-86684A describes that by an optical interference effect resulting from the respective layers, the transparent electrode pattern becomes a stealth pattern, and the color tone thereof becomes neutral.
In JP2010-152809A, before an ITO pattern is formed on a substrate, only on the lower side of the ITO pattern, a low-refractive index layer such as SiO2 and a high-refractive index layer such as Nb2O5 are laminated, and then the ITO pattern is formed. JP2010-152809A describes that in this way, it is possible to prevent the emergence of the shape of a transparent electrode pattern.
In JP2010-257492A, before an ITO pattern is formed on a substrate, only on the lower side of the ITO pattern, a low-refractive index layer such as SiO2 and a high-refractive index layer such as Nb2O5 are laminated. JP2010-257492A describes that in this way, it is possible to prevent a transparent electrode pattern or a crossing portion of patterns from becoming noticeable.
Various methods are known as methods for forming a transparent film such as a transparent insulating layer or a transparent protective film described in the aforementioned documents. Currently, as the smart phones or tablet PCs including a capacitive touch panel on a liquid crystal display or on an organic EL display, those using reinforced glass, which is represented by Gorilla Glass from Corning Inc., for a front panel (a surface that comes into direct contact with a finger) are being developed and presented. Furthermore, the smart phones or tablet PCs, in which an opening portion for installing a pressure-sensitive switch (a pressing-type mechanical mechanism that does not sense a change in capacitance) is formed in a portion of the front panel, are on the market. The reinforced glass has high strength and is not easily processed. Therefore, generally, in order to form the opening portion, the opening portion is formed prior to reinforcement processing, and then the reinforcement processing is performed.
As a method for forming a transparent insulating layer or a transparent protective film, WO2010/061744A or JP2010-061425A describes only a method of performing coating in a case of using an organic material. However, if a transparent insulating layer or a transparent protective film is formed on the aforementioned substrate, which has the opening portion and has undergone the reinforcement processing, by means of the coating method described in WO2010/061744A or JP2010-061425A by using the material described in the JP2010-257492A and WO2010/061744A, a resist component leaks or sticks out of the opening portion. Consequentially, a step of removing the sticking portion is necessary, and this leads to a problem of great reduction in production efficiency.
Meanwhile, JP2007-334045A and JP2008-107779A describe a transfer material for a color filter and suggest lamination of the transfer material on a substrate. However, although these documents made a mention of the use of the material in a liquid crystal display device, a method for improving the visibility of an ITO pattern was not examined in the documents. Moreover, the documents did not describe the application of the transfer material to a capacitive input device.